glx: fix glGetTexLevelParameteriv for indirect rendering

A single element in a GLX reply is contained in the header itself.
The number of elements is denoted in the "n" field of the reply.
If "n" is 1, the length of additional data is 0.
The XXX_data_length() function of xcb does not return the length of
the (optional, n>1) data but the number of elements.

Fixes http://bugs.freedesktop.org/show_bug.cgi?id=59876

Note: This is a candidate for the stable branches.

Signed-off-by: Stefan Brüns <[email protected]>
Signed-off-by: Brian Paul <[email protected]>
Reviewed-by: Ian Romanick <[email protected]>

1 files changed, 3 insertions, 1 deletions

diff --git a/src/mapi/glapi/gen/glX_proto_send.py b/src/mapi/glapi/gen/glX_proto_send.py
index fbc0dd3fab7..f4d519f144a 100644
--- a/src/mapi/glapi/gen/glX_proto_send.py
+++ b/src/mapi/glapi/gen/glX_proto_send.py
@@ -700,7 +700,9 @@ generic_%u_byte( GLint rop, const void * ptr )
                         if f.reply_always_array:
                             print '        (void)memcpy(%s, %s_data(reply), %s_data_length(reply) * sizeof(%s));' % (output.name, xcb_name, xcb_name, output.get_base_type_string())
                         else:
-                            print '        if (%s_data_length(reply) == 0)' % (xcb_name)
+                            print '        /* the XXX_data_length() xcb function name is misleading, it returns the number */'
+                            print '        /* of elements, not the length of the data part. A single element is embedded. */'
+                            print '        if (%s_data_length(reply) == 1)' % (xcb_name)
                             print '            (void)memcpy(%s, &reply->datum, sizeof(reply->datum));' % (output.name)
                             print '        else'
                             print '            (void)memcpy(%s, %s_data(reply), %s_data_length(reply) * sizeof(%s));' % (output.name, xcb_name, xcb_name, output.get_base_type_string())